Unlike oils that are usually liquid and plastic fats which display broad melting intervals, confectionary fats have a sharp melting interval at temperatures above 30° C. The fat most used for this purpose is cocoa butter (CB), which displays high level of triacylglycerols (TAG) with the general formula SUS (70-90%), where S represents a saturated fatty acid in the sn-1,3 position of the TAG and U represents unsaturated fatty acid in the sn-2 position of the TAG. The typical composition of CB is shown in Table 1A, 1,3-distearoyl-2-oleoyl-glycerol (StOSt), 1-palmitoyl-2-oleoyl-3-stearoyl-glycerol (POSt) and 1,3-dipalmitoyl-2-oleoyl-glycerol (POP) being the most abundant TAG species.
TABLE 1ATypical composition of the most abundant TAGs and TAGclasses of cocoa butters from different origins.GhanaIvory CoastBrazilTriacylglycerol (%)POP15.315.213.6POSt40.139.033.7StOSt27.527.123.8Triacylglycerol class (%)SSS0.70.6TraceSUS84.082.671.9SUU14.015.524.1UUU1.31.3 4.0P = palmitic acid;St = stearic acid;O = oleic acid;S = saturated fatty acid,M = monoenoic fatty acid andD = dienoic fatty acid,U = unsaturated fatty acid
The triacylglycerol composition of two cocoa butters and shea butter and their corresponding solid content between 30 and 40° C. are shown in Tables 1B and 2.
TABLE 1BTriacylglycerol composition of two cocoabutters (CB1 and CB2) and shea butter.Triacylglycerol composition (%)CB1CB2SheaPOP13.418.70.2POSt38.340.74.3PLP1.41.80.1POO2.33.01.7PLSt3.63.61.2POL0.30.40.5PLL<0.1<0.1<0.1StOSt31.924.041.3StOO3.83.827.5StLSt2.41.85.7OOO0.30.25.2StOL0.50.45.2OOL<0.1<0.11.3StLL<0.1<0.11.2OLL<0.1<0.10.4AOSt1.91.12.5OOA<0.10.11.5OLA<0.1<0.1<0.1P = palmitic acid;St = stearic acid;O = oleic acid;L = linoleic acid;A = araquidic acid;B = behenic acid
TABLE 2Content of solids at different temperatures of twococoa butters (CB1 and CB2) and shea butter.Temperature (° C.)/Solid content (%)30° C.32.5° C.35° C.37.5° C.40° C.CB161.143.626.513.85.8CB248.221.75.90.50.0Shea54.440.825.913.75.8P = palmitic acid;St = stearic acid;O = oleic acid;L = linoleic acid;A = araquidic acid;B = behenic acid
Cocoa butter displays a complex polymorphic behavior, with six crystalline forms that give place to five different polymorphs. Furthermore, the melting interval of this fat is very sharp. The physical properties of this fat confer to chocolate and confectionary products their typical characteristics involving high solid contents and quick melting in the mouth, conferring a fresh sensation and quickly releasing flavours.
The world production of CB is constrained by low productivity of cocoa tree, a restricted area of production and the attacks of pests on the crop. This situation contrasted with the increasing world demand of this fat, which causes tensions in this market involving frequent price raises.
The alternatives to CB for the production of confectionary fats consisted of palmitic and lauric fats obtained from palm, palm kernel or coconut oils or oils hardened by hydrogenation. Former fats are rich in palmitic, lauric and myristic fatty acids, displaying high levels of saturated fatty acids in the sn-2 position. These fats have been demonstrated to increase the levels of blood plasma cholesterol inducing arteriosclerosis.
The intake of hydrogenated fats is neither recommendable for cardiovascular health due to their content in trans-fatty acids that alter cholesterol metabolism, increasing the fraction associated to LDL proteins and decreasing the cholesterol associated to HDL ones. Alternative sources to CB are tropical fats rich in StOSt like shea, illipe, kokum or mango.
These sources of fat for confectionary products are not atherogenic but still their supply is not regular, provided these species are not usually crops but their fruits and seeds are harvested from the wild, moreover they are produced in areas with a poor communication and with irregular supply. These fats are usually mixed with some palm fractions rich in POP prior to be used in confectionary fat formulations.
Furthermore, in the last years new alternative sources of StOSt for confectionary have appeared. They come from oil crops that have been modified by genetic engineering by increasing their levels of stearic acid, such as soybean and oilseed rape. These are plants with seeds growing in green capsules or siliques, which involve the presence of linolenic acid in their oils in important amounts, and also linoleic acid. The presence of linolenic acid is not desired in confectionary fats due to the fact that it is unstable to oxidation and it possesses a very low melting point (−11° C.), which decreases their solid fat contents at room temperature or higher. These fats could be also used for plastic fats, to make spreads, shortening and margarine, displaying broad melting intervals. Examples of all these applications with fractionated oils can be found in WO99/57990 were high-stearic and high-oleic soybean oil is used to produce a fat suitable for confectionary, or in WO00/19832 were high-stearic and high-oleic rapeseed oil was used to make similar products, but unfortunately with some linolenic acid (18:3), and with less that 3% of solid content at temperatures above 33.3° C. This is useful to make shortening and spreads, but is less suitable for confectionary.
High-stearic and high-oleic sunflower oils have also been fractionated to obtain olein fractions for frying oils (WO2008/006597) and to produce a fat suitable for structuring a liquid vegetable oil, making a typical spreadable fat with broad melting point (WO01/96507).
A need remains for alternative fats for use in confectionary products.